A group of 18 high school students have been caught hacking people's online chat accounts to defraud their friends, VnExpress quoted Hanoi police as saying on Wednesday.

The group, whose members are studying at a school in the central province of Quang Tri, told police that they had cheated numerous people out of tens of millions dong, the news website reported.

Initial police reports said the group, led by 16-year-old Nguyen Duc Bi, sent links with hidden spy software to their targets via Yahoo! Messenger.

Once people clicked on the links, the software would install automatically on their computers, allowing the group to steal their chat accounts, police said.

After that the students would pose as their victims and asked people in their friend lists to help them top up mobile phone services by buying cards and sending them the cards' codes. Or, they would convince the victims' friends to buy online game cards.